export nfs gracer way in Linux

To reload /etc/exports, /sbin/exportfs is best way
to command it in standard.
It modify generic linux to check daemon status
before restart instead of restarting everytime.

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
Support slackware linux

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
fix typo for slackware

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
improve slackware/plamo detection and change nfs_check_command

* On Slackware, /etc/rc.d/rc.nfsd has no "status" argument, so the check command change to pidof command.
* On Plamo Linux, there is no /etc/slackware-release file, so use "/usr/lib/setup/Plamo-*" instead.
Merge pull request #2077 from miurahr/exportfs

Improvement of Linux supports and NFS handling using exportfs